Update: One of Rand's commenters claims that UN sanctions ended the nuclear program, but Rand notes:

If you read the Duelfer Report, it claims that he was planning to reconstitute his nuclear program as soon as sanctions were lifted and the heat was off. This (among other things) was the purpose of all the bribes to the French and Russians.

And Dennis Ray Wingo states one of Saddam's biggest excuses for restarting the nuke program:

The Frenchies and the Russians were pushing hard to get ALL sanctions lifted, starting with deauthorizing the no fly zones. When that happened the Kurds and Shiites would have been in deep Shiite. Then with all sanctions lifted and a huge resevoir of good well built up through billions of dollars worth of bribes, does ANYONE seriously think, especially with the Iranian ramp up in nuclear ambitions (remember Saddam was more scared of them than us) , that Saddam, in the face of complete impotence from the west in dealing with Iran, not restarted his program?